Background: Prophylaxis against thromboembolic complications has become routine after major trauma and major orthopaedic surgery. In contrast, it remains an issue for debate whether prophylaxis after minor surgery and immobilization is necessary, even though these treatments are well-known risk factors for deep vein thrombosis (DVT).

Objectives: The objective of this study was to evaluate the efficacy of Dalteparin (5,000 U given subcutaneously once daily for six weeks) during lower limb immobilization after surgical treatment of Achilles tendon rupture.

Methods: After surgery, 105 consecutive patients were randomized to a placebo-controlled double-blind study to evaluate the efficacy of given thromboprophylaxis. DVT screening using validated color duplex sonography was performed three weeks and six weeks after surgery, and all DVTs were confirmed with phlebography.

Results: Primary endpoint analysis was available for 91 patients. DVT was diagnosed in 16/47 patients (34%) in the Dalteparin group and in 16/44 patients (36%) in the placebo group. These figures are not significantly different (p=0.8). Proximal DVT was diagnosed in one patient (2%) in the Dalteparin group and in three patients (6%) in the placebo group (p=0.6). No pulmonary emboli or major bleeding occurred in either of the groups.

Conclusions: DVT is common after surgical treatment of Achilles tendon rupture and therefore effective thromboprophylaxis is desirable. Thromboprophylaxis with Dalteparin however, does not affect the incidence of DVT during the immobilization after Achilles tendon rupture surgery. Long-term effects of immobilization, such as the risk for post-thrombotic syndrome, need to be investigated further.